Method and apparatus for adjusting the working gap between the points of the flat clothings and the points of the cylinder clothings of a carding machine

ABSTRACT

A method and an apparatus for adjusting the working gap between the points of the flat clothings and the points of the cylinder clothings of a carding machine, with the flat rods provided with clothings being guided over a partial zone of the cylinder circumference on either side of the carding machine on respective convexly arched sliding guides, and the flat rods are provided with flat heads comprising sliding surfaces, which flat heads slide along the sliding guides, is characterized in that the adjustment of the working gap is performed by changing the radial height of the sliding surfaces of the flat heads with respect to the points of the respective flat clothing.

[0001] The present invention relates to a method and an apparatus foradjusting the working gap between the points of the flat clothings andthe points of the cylinder clothings of a carding machine, with the flatrods provided with clothings being guided over a partial zone of thecylinder circumference on either side of the carding machine onrespective convexly arched sliding guides, and the flat rods areprovided with flat heads comprising sliding surfaces, which flat headsslide along the sliding guides.

[0002] Apparatuses of this kind are known in different embodiments.

[0003] For example, the old U.S. Pat. No. 528,007 of Oct. 23, 1894describes a revolving flat card in which the flat rods which areprovided with flat clothings are fastened at their ends to respectiveendless chains and are pulled by means of said endless chains oversliding guides provided at either side of the carding machine, so thatthe clothing points are moved relative to the clothing points of thecylinder and at a constant distance from the same over a partial zone ofthe circumference of the cylinder and thus perform the desired cardingwork. After the movement along the sliding guides the flat rods aredeflected about a pair of chain wheels and guided back to a furtherchain wheel which is also used as a deflection point. In this way theyreach the sliding guides again, so that they can perform the desiredcarding work again with the clothing points of the cylinder. As aresult, the flat rods will repeatedly reach the sliding guide and willrepeatedly perform the carding work with the cylinder.

[0004] So-called flat heads are provided at the ends of the flat rodswhich are provided with sliding surfaces which slide on the respectivesliding guides on either side of the carding machine. Said slidingsurfaces determine in combination with the sliding surfaces of thesliding guides the distance between the points of the flat clothings andthe points of the cylinder clothings. This distance must be adjustedprecisely in the production of the card and when the carding machine isnewly clothed. Currently, carding distances, i.e. distances between thepoints of the flat clothings and the cylinder clothing, are desirable inthe range of approx. 0.2 mm. High-quality carding work at highproduction of the carding machine is only possible then.

[0005] In adjusting said carding gap, the sliding guide in the cardingmachine is radially adjusted according to U.S. Pat. No. 528,007 withrespect to the rotational cylinder axis in order to maintain the desiredcarding distance. For this purpose the sliding guides are arranged asso-called flexible bends which are attached according to the US patentspecification at three different places by means of adjusting rods tothe side frame of the card frame. By adjusting the adjusting rods, whichare arranged as threaded rods with left-handed and right-handed threads,the three points on which the adjusting rods act upon the flexible bendcan be adjusted with respect to the card frame and thus the cylinderaxis. It is necessary to understand that as a result of the radialadjustment at three circumferentially distributed points, the curvatureof the flexible bends, i.e. the sliding guides, is changed slightly,meaning that there is a bending of the flexible bends.

[0006] After adjusting the carding distance along the sliding guides,the carding machine can be put into operation. In the course of time thepoints of the flat clothings and the cylinder clothings are worn off, sothat the carding distance increases in an undesirable manner. In orderto counteract said enlargement of the carding distance, all adjustingrods can also be adjusted jointly in the old U.S. Pat. No. 528,007 inorder to return the carding distance to the originally provided value.

[0007] For this purpose the adjustable rods are not fastened directly tothe side frame of the card frame at their ends averted from the flexiblebend, but instead to the respective arms of angle levers which aremounted rotatably on the side frames of the card frame. The other armsof the respective angle levers are connected mutually and with anadjusting wheel via respective connecting rods, so that by turning theadjusting wheel there is a common adjustment of the angle levers andthus the respective points of attack of the adjusting rods on theflexible bends by way of the adjusting rods.

[0008] One can see therefrom that the basic setting is possible by theadjusting rods for each supporting point of the flexible bendindependent from the other supporting points and that accordingly it ispossible to carry out a common adjustment of all supporting points ofthe flexible bend, so that the carding gaps are adjusted evenly alongthe flexible bend. As was already mentioned, the flexible bends areslightly bent to adapt to the changed curvature.

[0009] A change in the settings of the flexible bends is not onlynecessary in the case of wear and tear of the flat clothings andcylinder clothings, but also after the grinding of the cylinder or flatclothings.

[0010] It is known to mount a grinding device on a card and, after theinterruption of the carding work, to grind the clothings during theirservice life once or twice or three times for example in order toprovide the clothing points both of the cylinder clothing as well as theflat rod clothings with a sharp shape which ensures a better quality ofthe carding work.

[0011] It is known from various patent specifications, e.g. from EP-A-0565 486, to install a grinding device in a carding machine which is usedsubstantially more frequently and during the production operation of thecarding machine in order to ensure that the respective clothings remainsharp. This latter possibility has the major advantage that the cardingmachine need not be stopped to grind the cylinder and flat clothings ofthe carding machine, thus avoiding any impairment to production.Moreover, it is ensured that the clothings always have optimal sharpnessand that thus a card sliver is always produced with even andhigh-quality properties, which benefits the subsequent production ofyarn. Moreover, such a grinding system will lead to the consequence thatthe clothings are generally provided with a longer life span.

[0012] Irrespective of whether the clothings are ground only a few timesduring their life with higher material removal or more frequently withless material removal, such grinding processes lead to changes in thecarding distance. The possibility of radial adjustment of the flexiblebends allows, however, setting the carding distance correctly at alltimes. Different further proposals have been made as to how one canachieve a radial adjustment of the flexible bends.

[0013] SACM offered a carding machine around 1975 for example in whichthe adjustment of the flats was performed on each side of the machinefrom a single point by means of two adjacent and mutually displaceablespirals.

[0014] In this construction, the outer spiral is provided on each sideof the carding machine with the shape of an long stretched-out bentwedge with a small wedge angle whose outside surface forms the slidingguide and whose inner radial surface slides on the radial outsidesurface of the respective inner spiral. The inner spirals are alsoprovided with the shape of a long stretched-out bent wedge, but areprovided in addition on the radial inner side with teeth and can thus beturned by means of a pair of toothed wheels about the axis of thecylinder, so that as a result of the cooperation of the radial outsidesurface of the inner spiral with the respective radial inner surfaces ofthe outer spirals, the sliding guides can be adjusted simultaneously onboth sides of the carding machine. As a result, all flats cansimultaneously approach or move away from the cylinder of the card. Itwas also known in this arrangement to slightly offset the cylindertowards the axis of the curved sliding guide in order to produce an“entrance” for the flat chain, meaning that the carding distance was setslightly larger in the zone where the flat rods approach one another atthe beginning of the carding path than at the end of the carding pathwhen they leave the cylinder in order to be returned thereafter to thebeginning of the carding path.

[0015] The same proposal was also newly made in DE 196 51 894 A1.

[0016] DE 29 48 825 A1 is also of major interest in connection with theadjustment of the flexible bends of a carding machine. It is recognizedthere that the carding distance can change during operation, namely bothas a result of extensions which are caused by centrifugal forces as wellas due to thermal extensions which occur during the heating or coolingof the carding machine.

[0017] Such extensions, which are caused due to centrifugal forces orfor thermal reasons, are particularly problematic during start-up orcut-off of the carding machine, as is explained in closer detail in DE-A29 48 825. As is explained there, the tendency to increase theproduction rate of carding machines leads to the consequence, on the onehand, that the speed of the processing elements is increased and, on theother hand, that the dimensions of the machine cylinders increase,namely both the diameter as well as the working width. As a result ofincreased rotational speeds and the increased dimensions, there can bean undesirable deformation of the cylinders, i.e. their bulging which iscaused by centrifugal force and which increases gradually.

[0018] It is also explained there that a further directly linkedinfluence in connection with the production rate and thus the cardingwork can be seen in the tendency to substantially suppress the exchangeof air between the cylinders and the ambient environment for preventingdust emissions, which makes the natural cooling of the working elementsmore difficult.

[0019] It is expressed in DE-A 29 48 825 that the temperature of theinvolved cylinders increases in the course of the operating time untilan equilibrium temperature is reached. This increase in temperaturecauses a change in the dimension of the cylinders and, especially, anincrease in the diameter of the cylinder. Both the influence of thecentrifugal force as well as the influence of the temperature rise donot have an immediate influence upon starting the machine, but onlyafter a certain delay which, relating to the influence of centrifugalforce, is at least as long as the acceleration time of the involvedelements, e.g. the swift in the carding machine.

[0020] The influence of the temperature rise until an equilibriumtemperature is reached usually continues over many longer periods ofoperation which can be several hours.

[0021] In order to remedy this, DE-A 29 48 825 provides a method tocontrol the working conditions between two working elements providedwith a pointed clothing, e.g. the cylinder and the revolving flat of arevolving flat card, in which a value which is in direct connection withthe dimensions of the cylinder is detected continuously or temporallyand the carding distance is kept to a certain value by a suitablecontrol means depending on the detected value.

[0022] The concrete solution shown there uses heatable metal rods foradjusting the flexible bends, i.e. the sliding guides, which are heatedeither by means of a fluid heatable by a heat supply apparatus or anelectric heating and are therefore caused to undergo a thermalextension. Since the temperature control allows a relatively precisesetting of the lengths of the respective metal rods, the device asdescribed there can work with a high precision.

[0023] Various other proposals are also known for the radial adjustmentof the flexible bends of a carding machine. For example, U.S. Pat. No.5,625,924 shows a carding machine with different possibilities for theradial adjustment of the sliding guide. Among other things, thisspecification describes the application of controllable actuators whichare triggered specifically to newly and periodically set the workingelements and to compensate the change of the carding gap as a result ofwear and tear to the clothings or after a grinding process. It isexpressed that the controllable actuator can be used and controlled inconnection with the built-in grinding system. Different arrangements ofthe actuator are indicated. For example, the application of servomotorsor piezoelectric translators for performing the adjustment is mentioned.It is also shown how an eccentric arrangement can be used by acontrollable drive mechanism to perform a smooth adjustment.

[0024] An adjusting system is further known from the WO 93/07314 withseveral adjusting devices which are arranged at respective places alongthe sliding guide and which extend between the sliding guide and a fixedreference point, with each adjusting device comprising a blocking modein which an adjustable clamping device is active in order to maintain aonce reached setting by way of clamping.

[0025] Despite the large number of proposals that have already beenmade, they are difficult and complex to realize in practice andexpensive to produce.

[0026] The extent of adjusting movements in the individual adjustingpoints of the flexible bend is relatively small. An overall adjustmentof more than three to four millimeters is rarely necessary. Anadjustment in steps of approx. 0.01 mm is desirable. As a result of suchsmall steps it can be easily understood that already small amounts ofplay in mechanical joints and the like will question the precision ofthe adjustment. Adjusting devices which are used with thermal extensionrequires a certain amount of control and can be impaired by dead play,since the setting requires a movement once radially to the outside and amovement once radially to the inside. The problem arises thattemperature measurements are indirect measurements and directmeasurements of the carding distance have proven to this date to berelatively imprecise.

[0027] Even in the case of adjustable wedge systems, the productioncosts are relatively high, since it is necessary that narrow tolerancesbe maintained over a wide range.

[0028] The applicant also noticed that the materials used for thesliding guide frequently show a hysteresis, so that the paths during theadvancement and retraction are not the same and the precision of theadjustment would suffer for this reason as well. The frictional forceswhich also occur in a number of constructions are so large that thereturning forces which arise due to the tension of the flexible bend aretoo small to precisely ensure a proper return.

[0029] A plastic deformation occurs in some materials already at lowertensions, which also leads to an imprecision of the adjustment. Thepretensions which are used in working the flexible bend can have adisturbing influence on the precision of the setting.

[0030] When there are windows in the flexible bend which are useful foradjusting the flats, then they can also disturb the constant progress ofthe carding gap in an unfavorable manner.

[0031] It is also known to radially adjust the flexible bends or slidingguides for the flat rods of a carding machine for various reasons,namely:

[0032] a) for newly setting the carding gap during the production of thecarding machine or after a renewed clothing of the carding machine, witha respective adjustment in the range of approx. 2 mm at the variousadjusting points being common practice in order to enable the setting ofthe carding distance along the sliding guide at all points;

[0033] b) in order to produce a radial adjustment of the sliding guidesin order to counteract any wearing effects of the clothings and to keepthe carding distance constant, with an even adjustment at the respectiveadjustment points being desirable, because one must assume even wear andtear and the once correctly set carding distance only needs to bereadjusted evenly;

[0034] c) in order to produce a radial adjustment of the sliding guidesin order to counteract the change of the carding distance after thegrinding of the clothings, with an even adjustment also only beingnecessary in this case too;

[0035] d) in order to carry out a radial adjustment of the flexiblebends so as to counteract the change of the carding distance due tocentrifugal force or thermal expansions, with this setting also beingunderstood as an even setting.

[0036] The adjustment range for all even settings (according to b), c)and d)) is usually in the range from 0.2 to 0.3 mm.

[0037] In all the proposals made up until now there is in the end abending of the sliding guides in order to achieve the requiredadjustment of the carding gap, so that the sliding guide is to beregarded as a flexible part, even if it partly shows a very highstiffness.

[0038] In order to effect the adjustment, the individual adjustingdevices are supported on relatively rigid constructions such as the sideframes of the carding frame or so-called fixed bends which in principlealso form an element of the side frame of the carding frame.

[0039] It is the object of the present invention to provide a method andan apparatus of the kind mentioned above which does not suffer theaforementioned disadvantages or only to a lower extent, provides asubstantial simplification in the zone of the flexible bend and allowsfixing the same after performing a one-off adjustment during theproduction of the carding machine or to even design the same as a fixedbend and thus ensure substantial savings in cost during the productionand operation of the carding machine, whereby a precise setting of thecarding gap over the entire effective range of the entirely presentadjustment still being enabled.

[0040] In order to solve this object is proceeded in respect of themethod in such a way that the setting of the working gap is performed bychanging the radial height of the sliding surfaces of the flat headswith respect to the points of the respective flat clothing. Preferably,an adjusting device is provided in or on each flat head whose radialheight is set for the purpose of setting the working gap.

[0041] By providing an adjusting device in or on the flat heads of theflat rods it is managed to achieve a substantial simplification in thearea of the flexible bend. The same can be aligned only once preciselywith respect to the rotational axis of the cylinder during theproduction of the carding machine, e.g. in such a way that the convexlyarched sliding guides are disposed concentrically to the rotational axisof the cylinder or extending wedge-like with respect to an imaginarycircle disposed concentrically to the rotational axis of the cylinder,so that the working gap between a flat clothing and the cylinderclothing decreases over the length of the sliding guide in the manner asis known per se. All settings made thereafter of the working gap can bemade by settings of the adjusting devices of the respective flat heads.

[0042] Since it is possible with modem working machines to preciselyproduce the convexly arched sliding guides on the side frames of thecarding machine concentrically to the rotational axis of the cylinder orwith a desired alignment relative to the rotational axis, it would evenbe possible to omit the so-called flexible bend and to work with only afixed bend which is provided with the convexly bent sliding surfaces forthe flat rods.

[0043] There is the principal possibility to provide the flat heads witha two-part arrangement and to produce either the one part of the flathead in a row of different radial thicknesses relating to the rotationalaxis of the cylinder and to choose the respective matching part in orderto determine the radial height of the working gap, with the two parts ofthe flat head then being tightly screwed together or fastened in anothermanner. Alternatively, individual spacing disks of selected thicknesscan be inserted between the two parts of the flat heads.

[0044] This type of setting which can be used for the above-mentionedcases a), b) and c) is simpler as compared with previous methods in therespect that it can be performed by an exchange of spacer elementsoutside of the carding machine, namely by employing a gauge whichconsiders the position of the clothing points of the cylinder, which caneasily be measured again from the outside, optionally after removing aflat rod, with respect to the radial position of the convexly bentsliding guides.

[0045] Even if it is deemed necessary to work with flexible bends, whichneed to be set once during the production of the carding machine, theuse of adjusting devices of the kind mentioned above represents a clearsimplification as compared with the renewed setting of the flexible bendfrom time to time.

[0046] Since there are no special limitations with respect to thethickness of the spacer elements, this type of adjustment can be usedboth for coarse setting as well as for the fine setting to the extentthat it is ensured by a precise working of the sliding guides that thesame are disposed concentrically to the rotational axis of the cylinderor have the desired position with respect to the rotational axis of thecylinder.

[0047] However, it is not possible when using spacer elements of fixeddimensions to make the setting in such a way that centrifugal forcesoccurring during operation or thermally induced changes of the workinggap can be considered in such a way that the working gap will alwaysremain constant.

[0048] In order to solve this partial task too, one can work with flatheads in which each adjusting device concerns a piezoelectric devicewhich is adjusted electrically to determine the radial height of theflat head.

[0049] Since piezoelectric devices are known which allow adjustments upto a number of millimeters (e.g. DE-A 198 33 782 describes apiezoelectric adjusting device in form of a drive arrangement for awriting head which achieves adjustments in the range of up to 2 mm), theuse of piezoelectric adjusting devices allows both performing the coarsesetting according to item a) as well as the settings according to itemsb), c) and d). The realization of the coarse setting according to itema) means under certain circumstances, however, that every piezoelectricdevice must be triggered separately in order to ensure differentadjustments in the respective flat heads.

[0050] Although this is principally possible, it is slightly morecomplex in realization. These complications can be avoided, however,when the piezoelectric adjusting device is used in combination with aspacer element, because the spacer elements can each be chosenindividually in the adjustment according to item a).

[0051] The fine adjustment according to items b), c) and d) which canonly be made in a range of approx. 0.2 mm can be achieved with apiezoelectric device very easily It is possible to adjust allpiezoelectric adjusting devices jointly, subject to the conditionhowever that the convexly arched guide surfaces have the desiredrelative position with respect to the rotational axis of the cylinder bya on-off setting or by precise working.

[0052] When the adjustment which is to be performed in each flat head isidentical with the adjustment which is desirable in every other flathead, such piezoelectric devices can be supplied with the requiredvoltage by a common voltage source via a common control device.

[0053] Another possibility to realize an adjusting device in accordancewith the invention is that the same is realized as a resilient devicewhose radial height with respect to the rotational axis of the cylinderis set by changing the tension of the belts which are provided formoving the flat heads along the sliding guides.

[0054] In the simplest of cases such an adjustable device can concern aspring, with the degree of compression of the respective spring beingchangeable by the belt tension. In order to change the belt tension, acontrollable brake may be provided which acts directly or indirectly atone of the deflection points of the endless belt on the toothed disksprovided there.

[0055] If the motor which causes the drive of the toothed disks whichproduce the drive for the endless belts concerns a type of motor whichalways tries to supply a constant drive output, it is sufficient to workwith such a controllable brake. If the drive output of the motordecreases with rising load, it may be advantageous to keep the driveoutput of the motor also controllable, so that in interaction with thecontrollable brake the belt tension in the zone of the convexly bentsliding guides and therefore the degree of compression of the spring canbe kept constant and adjustable.

[0056] The invention is now explained on the basis of mere examples byreference to embodiments shown in the drawings, wherein:

[0057]FIG. 1 shows a schematic representation of a conventional cardingmachine;

[0058]FIG. 2 shows a side view of the carding machine in FIG. 1 in thezone of the revolving flat for explanation in closer detail of the basicconstruction;

[0059]FIG. 3 shows a schematic cross section in the zone of therevolving flat of a carding machine as seen in the plane of intersectionIII-III of FIG. 2, with the representations of FIGS. 1, 2 and 3 beingshown on different scales;

[0060]FIG. 4 shows a schematic side view of a sliding guide for acarding machine with a flat head which slides thereon and is arrangedaccording to EP-A-0 753 610;

[0061]FIG. 5 shows a front view of a flat head similar to the one inFIG. 4, but according to a first embodiment of the invention;

[0062]FIG. 6 shows a representation similar to FIG. 5, but partlydisplayed in a cross-sectional view, of a variant of the flat head inaccordance with the invention with a built-in spring as an adjustingdevice;

[0063]FIG. 7 shows a side view of a flat head of FIG. 6 as seen in thedirection of arrow VIII;

[0064]FIG. 8 shows a top view of the spring of the flat head accordingto FIGS. 6 and 7:

[0065]FIG. 9 shows a representation according to FIG. 6, but of afurther embodiment in accordance with the invention with an oscillationdamper;

[0066]FIG. 10 shows a representation similar to FIG. 4, but with anarrangement of the flat head in accordance with the invention by using apiezoelectric adjusting device;

[0067]FIG. 11 shows a partly cut, enlarged view of the flat headaccording to FIG. 10 in order to illustrate a possible modification;

[0068]FIG. 12 shows a top view of the piezoelectric adjusting element ofFIG. 11, and

[0069]FIG. 13 shows an enlarged side view of the flat head of FIG. 10;

[0070]FIG. 1 shows in a side view a revolving flat card 10 as is known,e.g. the carding machine C50 of the applicant in a schematicrepresentation.

[0071] The fiber material to be carded which can consist of naturalfibers or synthetic fibers or mixtures thereof is supplied in the formof opened and cleaned flocks to the filling box 12, received by alicker-in or taker-in 14 as lap feed, transferred to a swift or cylinder16 and parallelized by a set of revolving flats 18 which is driven viadeflection pulleys 20, 22, 24, 26 in opposite direction to the directionof rotation 28 of the swift 16.

[0072] Fibers from the nonwoven disposed on the swift 16 are removed bya doffer 30 and formed into a card sliver 34 in the known manner in anoutlet section 32 consisting of several rollers. Said card sliver 34 isthen deposited by a coiler 36 in a transport can 38 in a cycloidalmanner.

[0073]FIGS. 2 and 3 show the card of FIG. 1 in the zone of the set ofrevolving flats on an enlarged scale and in further detail. Forillustration purposes only individual flat rods 40 are shown which allconsist of a supporting body 42 which is arranged as a hollow profileand carries the flat clothing 44, as well as two end heads 46 which areattached to the respective ends of the hollow-profile-like supportingbody, e.g. in such a way that they are inserted in the ends of thehollow profile and are connected with the hollow profile in apositive-locking way by a squeezing process which is described in detailin EP-A-627 507.

[0074] The concrete preferred arrangement of the flat heads 46 and thedrive belts 48 which drive the same is described in EP-A-753 610. Thebelts can be arranged especially according to FIG. 4 of the presentspecification. This arrangement is also shown in FIG. 4 of the presentapplication in further detail in a schematic exploded view.

[0075] Belt 48 is provided on one side, namely the inner side of FIG. 2,with teeth 48A which engage in teeth 48B of the toothed disks or toothedwheels 20 and 26, with only few teeth 48A and 48B being shown forillustration reasons. It is understood, however, that the entire innerside of the belt 48 is provided with teeth 48A and the entirecircumference of the toothed wheels 20 and 26 are provided withrespective teeth 48B. On the outside of belt 48 there are furtherbeam-like teeth or beams 48 which are arranged in pairs. In this casetoo only individual pairs 49 are shown for illustration reasons and eachpair of teeth 49 engages in a respective recess or hollow space 41 of arespective flat head, as is described in closer detail in EP-A-0 753610.

[0076] One can seen in FIG. 2 that the endless drive belts, of whichonly the one on the one side of the carding machine is shown, pull theflat rods 40 from an inlet point 50 on the right side of the drawingover a carding path along a sliding guide 52 comprising a flexible bend54 up to an outlet point 56 and that the flat rods 40 thereafter aredeflected about the toothed wheel 20 driving the illustrated drive beltand are guided back to the inlet point 50, with the drive belt beingdeflected by the further toothed wheel 26 directly before the inletpoint 50 and is supported between the two toothed wheels 20, 26 by twofurther supporting wheels 22, 24 and a support 58.

[0077] It is understood that an arrangement as shown in FIG. 2 is alsodisposed on the other side of the carding machine in the manner as knownper se, with the driven toothed wheels 20 being driven by a common shaft60 by a respective schematically shown motor 61 with a control unit 63,as a result of which the two toothed wheels 20 and therefore the twotoothed belts 48 with the flat rods 40 which are fastened thereto by wayof the pairs of teeth 49 revolve synchronously, so that the longitudinalaxes of the flat rods 40 always extend parallel to the drive axis 62 ofthe cylinder 16. This parallel position is always maintained during themovement with the flat chain. It is also understood that in operationthe flat rods 40 are evenly distributed over the entire length of thedrive belts 48.

[0078] As is described in EP-A-753 610 in closer detail, the slidingsurfaces 64 of the flat rods 46 are disposed in the zone of the flexiblebend 54 in sliding contact with the same, namely as a result of its ownweight on the one hand and due to the belt tension on the other handwhich in the zone of each flat head produces a radially inwardlydirected force. In other words, they are pressed by the tension of thedrive belt 48 and due to their own weight against the sliding guide 52,i.e. against the sliding surfaces 66 of the flexible bend 54. In thisway the required carding distance A (FIG. 3) between the flat clothings44 and the cylinder clothing 68 is ensured. Due to the positive-lockingengagement of the pairs of beams 49 of the drive belt 48 in therespective openings 41 of the flat heads, and due to the synchronizedrevolving of the drive belts 48 on both sides of the carding machine,the flat rods 40 are moved in a synchronized way over the two flexiblebends 54, with the longitudinal axes of the flat rods 40 always beingguided parallel to the cylinder axis.

[0079] The positive-locking engagement between the drive belts 48 andthe flat heads 46 transmits the tensile forces of the drive belts 48onto the flat rods 40, so that they are moved along the carding pathbetween the inlet point 50 and the outlet point 56.

[0080] In this embodiment there is provided according to the presentdoctrine next to the toothed wheel 26 and mounted on its shaft 81, abrake disk 25 and brake nippers 27 which can be controlled by a controlunit 29 in such a way that a controlled brake force can be exerted onthe toothed wheel 26 (and via shaft 182) on the respective toothed wheelon the other side of the carding machine, as a result of which it ispossible to determine the belt tension on both sides of the cardingmachine and therefore the pressing pressure between the flat heads andthe sliding guides 66, as will be explained below in closer detail.

[0081] A particularity in the proposal according to EP-A-753 610 is thatin the zone of the deflection the beams of the pairs of beams 49 of thedrive belts 48 have a tendency to straddle apart and to hold the flatheads 46 in such a way that they are deflected about the toothed wheels20, 26 without there being any danger that the flat rods 40 are lost andwithout additional guide means being necessary in these zones.

[0082] On the upper side of the revolving flat 18 the flat rods 40 restloosely on the upper strands of the drive belts; they can thus be easilydetached from the drive belt 48 when they need to be especially cleanedor exchanged. Gravity ensures that the flat rods 40 will not separatefrom the drive belts 48 in this zone in an undesirable manner.

[0083] As can be seen from the sectional drawing of FIG. 3, the flexiblebends 54 of the sliding guides 52 will ensure defining the cardingdistance A between the flat clothings 44 and the cylinder clothing 68which are shown for reasons of illustration only in sections in FIGS. 3and 4 The sliding guides in this example are equipped with an embeddedbelt-like guide element 70 made of plastic which forms the slide surfacefor the flat heads, as is described in closer detail in DE-A-39 07 396or EP-A-0 620 296. Principally, such an embedded element or embeddedelements which are subdivided into sections can be used in allembodiments in accordance with the invention as explained below in orderto form the actual sliding surface 66 for the flat heads 46. Such anelement can also be omitted, however, especially when the flat head isprovided with a sliding block or sliding lining which slides on thesliding guide which usually consists of metal.

[0084]FIG. 3 also shows that each sliding guide 52 also comprises aradial inner support 72 which is frequently also known as a fixed bend,with each radial inner support 72 being rigidly connected with therespective associated side frame 74 of the carding machine or beingintegrally arranged with the same, e.g. in form of a respective castpart. The side frames 74 of the carding machine also carry therotational shaft 62 of the cylinder (not shown in FIG. 3) and also forma radial guide means for the flexible bends 54 (not shown).

[0085] Between each radial inner support 72 and the flexible bends 54associated to the same there are, as can be seen in FIGS. 2 and 3, fivelength-adjustable devices 76 in this example which consist of an innerpart 78 provided with an external thread and an outer part 80 arrangedas a threaded bush with inner threads. By turning the inner part 78 withrespect to the outer part 80 the length of the respective adjustingdevice 76 can be set. Accordingly, a radial adjustment of the flexiblebend 54 can be performed in the zone of the respective supporting point.As a result, the curvature of the respective flexible bend 54 can beadjusted to the curvature of the cylinder and the radial position of thesliding surface 66 and the respective flexible bends 54 can be set insuch a way that the carding distance A remains constant over the entirelength of the carding path and over the entire width of the cylinder,or—if desired—is provided with the desired course along the cardingpath.

[0086] In the description below the parts which correspond to the partas described above are identified with the same reference numerals, butincreased by the basic number 100, 200, etc. in order to bring about aclear decision. It is understood that the description up until now alsoapplies to parts which have the same end numerals, so that thisdescription need not be repeated again. This means that the descriptionbelow concentrates on the departing features.

[0087]FIG. 5 shows a face view at first which as seen approximately inthe direction of arrow V in FIG. 4 shows a flat head 146 which is alsoprovided with a hollow space 141 for receiving the pairs of teeth 49 ofthe drive belt.

[0088] In this embodiment a spring clip 190 is provided with tworesilient legs 192 which engage in respective undercuts 194 in the sideparts 147 of the flat head 146. Due to the inclined flanks of theundercuts 194 the spring clip 190 always tries to slip upwardly in FIG.5 and holds in this way a plate-like spacer element 196 between itslower zone 198 in FIG. 5 and the lower side 199 of the main body of theflat head.

[0089] The spring clip is of an at least substantially constant crosssection in this embodiment and extends in the direction perpendicular tothe illustration of FIG. 5 over a length which corresponds at leastsubstantially to the width B of the sliding guide 52.

[0090] One can see immediately that by using different spacer elements196 which also have a width perpendicular to the plane of the drawing ofFIG. 5 which at least substantially corresponds to the width B of thesliding guide 52, the distance A can be newly set. The spring clips canbe loosened and removed easily for exchanging the spacer elements 196.The lower side of the spring clip 190 forms in this example the actualsliding surface 164 of the flat head and can be provided for thispurpose with a hard surface or with a sliding lining. There is thefurther possibility (which is not shown in FIG. 5) to provide the springclip 190 with a slightly hollow arrangement in the floor zone 198, sothat two plane or curved sliding surfaces are obtained which correspondto the above sliding surfaces 64 of the flat head and the same thusassumes a stable position on the curved sliding guide 52.

[0091] In other words, the use of different spacer elements 196 allowschanging the radial height (relating to the rotational shaft of thecylinder) between the points of the flat clothings 44 and the actualsliding surface 164, i.e. in this example the lower side of spring clip190, and thus to set the working distance A.

[0092] In the embodiment according to FIG. 5 there is a furtherpossibility of setting the working distance A, namely by using a part196 with marked elastic and flexible properties.

[0093] As has already been explained, the belt tension leads to a forcecomponent which presses the flat heads 146 of the flat rods against thesliding surfaces 66 of the sliding guides 52. Since one is able toprovide this force variably according to the invention, one can alsodetermine the degree of compression of such spring elements 196 and thusalso the working distance A.

[0094] If a controllable brake (brake disk 25, brake nippers 27 andcontrol unit 29) is used according to FIG. 2, the belt tension can bedetermined according to the pressing pressure of the brake nippers 27 onthe brake disk 25 which is determined by control unit 29, and thus themagnitude of the force component acting in the radial direction on theflat heads.

[0095] If the drive motor 61 concerns a type of motor which always triesto maintain a predetermined speed and therefore increases the drivingtorque according to the respective load in order to maintain therequired rotational speed, no special control unit is required for thedrive motor 61 other than a control unit which ensures the requiredrotational speed (if the rotational speed belongs to the predeterminableparameters).

[0096] If a type of motor is concerned which responds to changing loadswith changing speeds so that it is difficult to achieve the belt tensionalone via the controllable brake, it may be advantageous to provide thedrive motor 61 with a control unit 62 which ensures a constant drivetorque at constant speed, e.g. by changing the amplitude of the voltageapplied on the motor or by controlling the drive current.

[0097] One can thus see that by increasing the belt tension it ispossible to also change the degree of compression of the spring elements196.

[0098] The embodiment according to FIGS. 6, 7 and 8 also uses springelements which in this case are in the form of leaf springs 296 whichare disposed between a fixed part 300 and a movable beam 302 of the flathead 246, namely to the left and right of the hollow space 241,receiving the pairs of teeth 49 of the endless belt 48. Each movablepart 302 of the flat head 246 is held displaceably on the shaft part 304by two guide pins 306 for the purpose of displacement according to thedouble arrow 308. The threaded part 301 of each guide pin 306 is screwedinto the fixed part 300 of the flat head 246, so that a shoulder of theguide pin rests fixedly on the fixed part 300. On the other hand, thehead part 303 of each guide pin is housed in a circular recess 305 ofthe movable part 302. The lower side of each movable beam 302 forms inthis example the sliding surface 264 of the flat head in the zonebetween the recesses 305.

[0099] A gap space 307 is situated between the movable beam 302 and thefixed part 300, in which space there is housed a spring element 296which is bent in the manner of a leaf spring, with each leaf spring 296having two openings 309 arranged as oblong holes through which projectsone each of the guide pins 306. In this way the springs are heldcaptively and can be freely compressed or stretched in the desiredamount without being hindered in their respective movements by the guidepins 306.

[0100] In this case to the degree of compression of the spring elements296 is influenced by the belt tension. This means that the radial heighth of the gap space 307 is determined by the belt tension and thereforealso the working distance A.

[0101]FIG. 7 also shows the part 311 of the flat head which is receivedwithin the hollow section 42 of the flat rod 40. One also sees in FIG. 7the recess 313 which receives the belt part of the belt and ensures thatthe flat heads are guided laterally by the endless belts.

[0102]FIG. 9 shows an embodiment which is very similar to the embodimentaccording to FIGS. 6 to 8, which is indicated by the applied referencenumerals. The only difference in this case is the provision of afriction lining 315 on the lateral zones of the fixed part 400 which areopposite of the movable beam 402. The fiction linings 315 act in anenergy-absorbing way and prevent oscillations in the springs leading tochanges in the working distance A. Instead of applying the frictionlinings 315 on the fixed part 400, they could optionally also beattached to the movable beam 402. If desired, spacer elements (notshown), could be inserted into the gap spaces in order to either performthe setting a) or to compensate possible differences of the springproperties.

[0103] The embodiment according to FIGS. 10 to 13 shows an alternativeembodiment of a flat head 446 which in this case too consists of twoparts, namely a part 500 which is fastened to a hollow carrier 442 ofthe flat rod and is thus designated as a fixed part and a movable partor beam 502 which is connected to the fixed part 500 by way of apiezoelectric adjusting device 496.

[0104] The piezoelectric device 496 consists in this case of a pluralityof piezoelectric layers which change their thickness by applying avoltage and thus cause the desired change in the radial height of thesliding surfaces 499 of the flat head 446 with respect to the clothingpoints of the flat rod 40. In order to produce this difference involtage a voltage is applied to one side of the piezoelectric device 496via a conducting track 519 which is integrated in the endless belt 448and extends at least partly completely through the belt, whereas theother side of the piezoelectric device 496 and the sliding guides 52 ofthe carding machine are applied to a ground.

[0105] One can use the parts 500 and 502 of the flat heads per se forthe electric connection between conducting track 519 and thepiezoelectric device 496 and between the piezoelectric device 496 andthe sliding guide 52. Alternatively, wires can be integrated in the flathead, as is shown in 523, in order to avoid voltage losses which wouldoccur under certain circumstances depending on the material of the flathead.

[0106] It is also possible, as shown in FIG. 11, to provide especiallyconductive coatings or linings in the zone of the sliding surfaces 466and in the zone of the contact point with the conducting track asinstalled in the endless belt 448.

[0107] It is also possible to install two conducting tracks 519 in theendless belt which are mutually insulated (since the endless belt partlyconsists of plastic) and to provide the voltage supply for thepiezoelectric device 496 via said two conducting tracks.

[0108] Since the conducting track is provided at either side of theendless belt 519, there can be a contact making with the conductingtrack on the inner side of the endless belt for the purpose of contactmaking with the voltage source or with the control device whichdetermines the level of the voltage and therefore the amplitude of thechange in dimension of the piezoelectric device 496. This can beperformed by way of brush-type contacts or respective conductive zonescan be provided on the toothed wheels which are in connection with avoltage source or a control device via brush-type contacts.

[0109] When zones of the toothed wheels are used for the voltagetransmission it must be ensured that the respective zones are insulatedfrom the remaining zones in order to avoid any shorts.

[0110]FIG. 12 shows that the piezoelectric device is N-shaped in a topview according to the shape of the flat head 446. FIG. 13 also showsthat there is a gap, which can also be provided with insulation, betweenthe two parts 500 and 502 of the flat head 446 in order to preventshorts in this case as well.

[0111] In all embodiments explained up until now the hollow space 41,141, 241, 341 and 441 is open on the outside face side, but closed onthe rear face side by the material of the flat head. It is notmandatorily necessary, however, to provide such a hollow space. It isonly provided here because endless drive belts with pairs of teeth areused which engage in hollow spaces. If no hollow space is provided, thespring device or piezoelectric device can be defined differently inorder to consider the respective shape of the flat head. When providinga hollow space the outside face side of the flat head can be closed off.A respective modified shape of the spring device or piezoelectric deviceis also possible, e.g. such that the piezoelectric device 496 of FIG. 12is provided then with the shape of a rectangle with a rectangularopening in the middle.

[0112] Although the piezoelectric device used here is represented as aplurality of piezoelectric layers, the piezoelectric device can berealized in a completely different way, e.g. according to theaforementioned German patent application 196 51 894 A1. It can then havea completely different orientation in the flat head.

1. A method for adjusting the working gap (A) between the points of theflat clothings (44) and the points (68) of the cylinder clothing of acarding machine (10), with the flat rods (40) which are provided withclothings being guided over a partial zone of the circumference of thecylinder on both sides of the carding machine on respective convexlycurved sliding guides (52) and the flat rods comprise flat heads (146;246, 346; 446) having sliding surfaces (164; 264; 364; 464) which slidealong the sliding guides (52), characterized in that the adjustment ofthe working gap (A) is performed by changing the radial height of thesliding surfaces (164; 264; 364; 464) of the flat heads (146; 246; 346;446) with respect to the points of the respective flat clothing (44). 2.A method as claimed in claim 1, characterized in that an adjustabledevice (196; 296; 396; 496) is provided in or on each flat head (146;246; 346; 446) whose radial height is set for adjusting the working gap.3. A method as claimed in claim 2, characterized in that each adjustabledevice concerns a piezoelectric device (496) which is electricallyadjusted to define the radial height.
 4. A method as claimed in claim 2,characterized in that each adjustable device concerns a resilient device(196; 296; 396) whose radial height is set by changing the tension ofthe belts (48) which are provided for moving the flat heads along thesliding guides.
 5. An apparatus for adjusting the working gap (A)between the points of the flat clothings (44) and the points (68) of thecylinder clothing of a carding machine (10), with the flat rods (40)which are provided with clothings being guided over a partial zone ofthe circumference of the cylinder on both sides of the carding machineon respective convexly curved sliding guides (52), with the flat rodscomprising flat heads (146; 246; 346; 446) having sliding surfaces (164;264; 364; 464) which slide along the sliding surfaces of the slidingguides, characterized in that in each flat head (146; 246; 346; 446) theradial height of its sliding surfaces (164; 264; 364; 464) is changeablewith respect to the points (44) of the respective flat clothing.
 6. Anapparatus as claimed in claim 5, characterized in that a device (196;296; 396; 496) is provided in or on each flat head (146; 246; 346; 446),which device is adjustable in its radial height (relating to therotational shaft of the cylinder).
 7. An apparatus as claimed in claim6, characterized in that each adjustable device (496) concerns apiezoelectric device.
 8. An apparatus as claimed in claim 7,characterized in that the piezoelectric devices (496) in the respectiveflat heads (446) can be driven by a common voltage source for adjustingthe working gap (A) by means of a control device.
 9. An apparatus asclaimed in claim 7 or 8, characterized in that in the known mannerendless belts (48) are provided for moving the flat rods (446) over thesliding guides, the endless belts are each provided with at least oneconducting track (519) extending over the entire length of the endlessbelt in order to ensure the voltage supply of the piezoelectric device,with a contact device being provided in at least one zone of thecircumferential path of each endless belt in order to ensure an electriccontact between the respective conducting track and the voltage source.10. An apparatus as claimed in claim 9, characterized in that thecontact device concerns a conductive brush.
 11. An apparatus as claimedin claim 9, characterized in that the endless belts (48) can bedeflected via toothed disks (20, 26) and deflection pulleys (22, 24),with a toothed disk or a deflection pulley being used for each endlessbelt as a contact device.
 12. An apparatus as claimed in claim 9 or 10,characterized in that each endless belt comprises two conducting tracks.13. An apparatus as claimed in claim 5, characterized in that theadjustable device concerns a spring (196; 296; 396) and that the degreeof compression of the respective spring can be changed by the belttension.
 14. An apparatus as claimed in claim 13, characterized in thatfor the purpose of changing the belt tension, a controllable brake (25,27, 29) is provided which acts at one of the deflection points of theendless belt directly or indirectly upon the toothed disks (26) providedthere.
 15. An apparatus as claimed in claim 14, characterized in thatthe drive output of the motor (61) provided for driving the tootheddisks (20) causing the drive of the endless belts (48) is controllable.16. An apparatus as claimed in claim 15, characterized in that a controldevice (63) is provided for controlling the output of the drive motor.17. An apparatus as claimed in claim 13, characterized in that eachspring device (396) is associated with an oscillation damper (315). 18.An apparatus as claimed in one of the claims 13 to 17, characterized inthat the springs (196) concern resilient, plate-like, elastic elements.19. An apparatus as claimed in claim 18, characterized in that eachplate-like element (196) is held on the flat head with a spring clip(190).
 20. An apparatus as claimed in one of the claims 13 to 17,characterized in that the springs (296; 396) concerning leaf springswhich are each disposed between a fixed part (300; 400) of the flat head(346; 446) and a part (302; 402) of the flat head which is displaceablyguided with respect to said head.
 21. An apparatus as claimed in one ofthe claims 5 to 20, characterized in that each flat head (146; 246; 346;446) is provided with a multipart arrangement and is arranged as anexchangeable spacer element (196).